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Dobson SJ, Ward JC, Herod MR, Rowlands DJ, Stonehouse NJ. A highly discriminatory RNA strand-specific assay to facilitate analysis of the role of cis-acting elements in foot-and-mouth disease virus replication. J Gen Virol 2023; 104. [PMID: 37436428 DOI: 10.1099/jgv.0.001871] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/13/2023] Open
Abstract
Foot-and-mouth-disease virus (FMDV), the aetiological agent responsible for foot-and-mouth disease (FMD), is a member of the genus Aphthovirus within the family Picornavirus. In common with all picornaviruses, replication of the single-stranded positive-sense RNA genome involves synthesis of a negative-sense complementary strand that serves as a template for the synthesis of multiple positive-sense progeny strands. We have previously employed FMDV replicons to examine viral RNA and protein elements essential to replication, but the factors affecting differential strand production remain unknown. Replicon-based systems require transfection of high levels of RNA, which can overload sensitive techniques such as quantitative PCR, preventing discrimination of specific strands. Here, we describe a method in which replicating RNA is labelled in vivo with 5-ethynyl uridine. The modified base is then linked to a biotin tag using click chemistry, facilitating purification of newly synthesised viral genomes or anti-genomes from input RNA. This selected RNA can then be amplified by strand-specific quantitative PCR, thus enabling investigation of the consequences of defined mutations on the relative synthesis of negative-sense intermediate and positive-strand progeny RNAs. We apply this new approach to investigate the consequence of mutation of viral cis-acting replication elements and provide direct evidence for their roles in negative-strand synthesis.
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Affiliation(s)
- Samuel J Dobson
- School of Molecular and Cellular Biology and Astbury Centre for Structural Molecular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Joseph C Ward
- School of Molecular and Cellular Biology and Astbury Centre for Structural Molecular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Morgan R Herod
- School of Molecular and Cellular Biology and Astbury Centre for Structural Molecular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - David J Rowlands
- School of Molecular and Cellular Biology and Astbury Centre for Structural Molecular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
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2
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Polio and Its Epidemiology. Infect Dis (Lond) 2023. [DOI: 10.1007/978-1-0716-2463-0_839] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/10/2023] Open
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3
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Persistent Enterovirus Infection: Little Deletions, Long Infections. Vaccines (Basel) 2022; 10:vaccines10050770. [PMID: 35632526 PMCID: PMC9143164 DOI: 10.3390/vaccines10050770] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Revised: 05/04/2022] [Accepted: 05/10/2022] [Indexed: 01/27/2023] Open
Abstract
Enteroviruses have now been shown to persist in cell cultures and in vivo by a novel mechanism involving the deletion of varying amounts of the 5′ terminal genomic region termed domain I (also known as the cloverleaf). Molecular clones of coxsackievirus B3 (CVB3) genomes with 5′ terminal deletions (TD) of varying length allow the study of these mutant populations, which are able to replicate in the complete absence of wildtype virus genomes. The study of TD enteroviruses has revealed numerous significant differences from canonical enteroviral biology. The deletions appear and become the dominant population when an enterovirus replicates in quiescent cell populations, but can also occur if one of the cis-acting replication elements of the genome (CRE-2C) is artificially mutated in the element’s stem and loop structures. This review discusses how the TD genomes arise, how they interact with the host, and their effects on host biology.
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Higher-order structures of the foot-and-mouth disease virus RNA-dependent RNA polymerase required for genome replication. Commun Biol 2022; 5:61. [PMID: 35039618 PMCID: PMC8764057 DOI: 10.1038/s42003-021-02989-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Accepted: 12/20/2021] [Indexed: 11/23/2022] Open
Abstract
Replication of many positive-sense RNA viruses occurs within intracellular membrane-associated compartments. These are thought to provide a favourable environment for replication to occur, concentrating essential viral structural and nonstructural components, as well as protecting these components from host-cell pathogen recognition and innate immune responses. However, the details of the molecular interactions and dynamics within these structures is very limited. One of the key components of the replication machinery is the RNA-dependent RNA polymerase, RdRp. This enzyme has been shown to form higher-order fibrils in vitro. Here, using the RdRp from foot-and-mouth disease virus (termed 3Dpol), we report fibril structures, solved at ~7-9 Å resolution by cryo-EM, revealing multiple conformations of a flexible assembly. Fitting high-resolution coordinates led to the definition of potential intermolecular interactions. We employed mutagenesis using a sub-genomic replicon system to probe the importance of these interactions for replication. We use these data to propose models for the role of higher-order 3Dpol complexes as a dynamic scaffold within which RNA replication can occur. Loundras et al. report on the fibril components of the RNA-dependent RNA polymerase RdRp from foot-and-mouth disease virus. They demonstrate that higher-order fibril-based interactions create multiple complex structures within which RNA replication can occur.
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Isolation and Identification of Inter-Species Enterovirus Recombinant Genomes. Viruses 2021; 13:v13122390. [PMID: 34960659 PMCID: PMC8703282 DOI: 10.3390/v13122390] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Revised: 11/16/2021] [Accepted: 11/26/2021] [Indexed: 11/25/2022] Open
Abstract
Positive-strand RNA virus evolution is partly attributed to the process of recombination. Although common between closely genetically related viruses, such as within species of the Enterovirus genus of the Picornaviridae family, inter-species recombination is rarely observed in nature. Recent studies have shown recombination is a ubiquitous process, resulting in a wide range of recombinant genomes and progeny viruses. While not all recombinant genomes yield infectious progeny virus, their existence and continued evolution during replication have critical implications for the evolution of the virus population. In this study, we utilised an in vitro recombination assay to demonstrate inter-species recombination events between viruses from four enterovirus species, A-D. We show that inter-species recombinant genomes are generated in vitro with polymerase template-switching events occurring within the virus polyprotein coding region. However, these genomes did not yield infectious progeny virus. Analysis and attempted recovery of a constructed recombinant cDNA revealed a restriction in positive-strand but not negative-strand RNA synthesis, indicating a significant block in replication. This study demonstrates the propensity for inter-species recombination at the genome level but suggests that significant sequence plasticity would be required in order to overcome blocks in the virus life cycle and allow for the production of infectious viruses.
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6
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Imprecise recombinant viruses evolve via a fitness-driven, iterative process of polymerase template-switching events. PLoS Pathog 2021; 17:e1009676. [PMID: 34415977 PMCID: PMC8409635 DOI: 10.1371/journal.ppat.1009676] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Revised: 09/01/2021] [Accepted: 08/08/2021] [Indexed: 02/07/2023] Open
Abstract
Recombination is a common feature of many positive-strand RNA viruses, playing an important role in virus evolution. However, to date, there is limited understanding of the mechanisms behind the process. Utilising in vitro assays, we have previously shown that the template-switching event of recombination is a random and ubiquitous process that often leads to recombinant viruses with imprecise genomes containing sequence duplications. Subsequently, a process termed resolution, that has yet to be mechanistically studied, removes these duplicated sequences resulting in a virus population of wild type length genomes. Using defined imprecise recombinant viruses together with Oxford Nanopore and Illumina high throughput next generation sequencing technologies we have investigated the process of resolution. We show that genome resolution involves subsequent rounds of template-switching recombination with viral fitness resulting in the survival of a small subset of recombinant genomes. This alters our previously held understanding that recombination and resolution are independent steps of the process, and instead demonstrates that viruses undergo frequent and continuous recombination events over a prolonged period until the fittest viruses, predominantly those with wild type length genomes, dominate the population. Viruses with positive-sense RNA genomes, such as poliovirus, have several mechanisms by which they evolve. One of these is the process of recombination involving the large-scale exchange of genetic information. Recombination occurs during replication when the viral polymerase, bound to the nascent RNA chain, switches from copying one genome to another. However, the polymerase does not always accurately switch between the two, resulting in sequence duplications or deletions, and genomes that are referred to as imprecise. Over multiple rounds of replication sequence duplications are lost and genomes are resolved to wild type length, but it is unclear how this occurs. Here we used synthetic polioviruses containing defined sequence duplications to determine that the genome population undergoes repeated rounds of recombination until sequence duplications are lost and viruses with precise, wild type length genomes are selected for. This selection is based on the overall fitness of the virus population, with less fit imprecise viruses evolving more quickly. Our study suggests that recombination is a continual process where virus fitness drives the selection of a small subset of recombinant variants. These data are important for understanding how novel viruses evolve via recombination and how this process can be blocked to prevent novel and dangerous pathogens from arising.
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Eruera AR, McSweeney AM, McKenzie-Goldsmith GM, Ward VK. Protein Nucleotidylylation in +ssRNA Viruses. Viruses 2021; 13:1549. [PMID: 34452414 PMCID: PMC8402628 DOI: 10.3390/v13081549] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 07/30/2021] [Accepted: 08/02/2021] [Indexed: 12/22/2022] Open
Abstract
Nucleotidylylation is a post-transcriptional modification important for replication in the picornavirus supergroup of RNA viruses, including members of the Caliciviridae, Coronaviridae, Picornaviridae and Potyviridae virus families. This modification occurs when the RNA-dependent RNA polymerase (RdRp) attaches one or more nucleotides to a target protein through a nucleotidyl-transferase reaction. The most characterized nucleotidylylation target is VPg (viral protein genome-linked), a protein linked to the 5' end of the genome in Caliciviridae, Picornaviridae and Potyviridae. The nucleotidylylation of VPg by RdRp is a critical step for the VPg protein to act as a primer for genome replication and, in Caliciviridae and Potyviridae, for the initiation of translation. In contrast, Coronaviridae do not express a VPg protein, but the nucleotidylylation of proteins involved in replication initiation is critical for genome replication. Furthermore, the RdRp proteins of the viruses that perform nucleotidylylation are themselves nucleotidylylated, and in the case of coronavirus, this has been shown to be essential for viral replication. This review focuses on nucleotidylylation within the picornavirus supergroup of viruses, including the proteins that are modified, what is known about the nucleotidylylation process and the roles that these modifications have in the viral life cycle.
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Affiliation(s)
| | | | | | - Vernon K. Ward
- Department of Microbiology & Immunology, School of Biomedical Sciences, University of Otago, PO Box 56, Dunedin 9054, New Zealand; (A.-R.E.); (A.M.M.); (G.M.M.-G.)
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Holmes AC, Zagnoli-Vieira G, Caldecott KW, Semler BL. Effects of TDP2/VPg Unlinkase Activity on Picornavirus Infections Downstream of Virus Translation. Viruses 2020; 12:E166. [PMID: 32023921 PMCID: PMC7077319 DOI: 10.3390/v12020166] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2019] [Revised: 01/20/2020] [Accepted: 01/22/2020] [Indexed: 12/12/2022] Open
Abstract
In this study, we characterized the role of host cell protein tyrosyl-DNA phosphodiesterase 2 (TDP2) activity, also known as VPg unlinkase, in picornavirus infections in a human cell model of infection. TDP2/VPg unlinkase is used by picornaviruses to remove the small polypeptide, VPg (Virus Protein genome-linked, the primer for viral RNA synthesis), from virus genomic RNA. We utilized a CRISPR/Cas-9-generated TDP2 knock out (KO) human retinal pigment epithelial-1 (hRPE-1) cell line, in addition to the wild type (WT) counterpart for our studies. We determined that in the absence of TDP2, virus growth kinetics for two enteroviruses (poliovirus and coxsackievirus B3) were delayed by about 2 h. Virus titers were reduced by ~2 log10 units for poliovirus and 0.5 log10 units for coxsackievirus at 4 hours post-infection (hpi), and by ~1 log10 unit at 6 hpi for poliovirus. However, virus titers were nearly indistinguishable from those of control cells by the end of the infectious cycle. We determined that this was not the result of an alternative source of VPg unlinkase activity being activated in the absence of TPD2 at late times of infection. Viral protein production in TDP2 KO cells was also substantially reduced at 4 hpi for poliovirus infection, consistent with the observed growth kinetics delay, but reached normal levels by 6 hpi. Interestingly, this result differs somewhat from what has been reported previously for the TDP2 KO mouse cell model, suggesting that either cell type or species-specific differences might be playing a role in the observed phenotype. We also determined that catalytically inactive TDP2 does not rescue the growth defect, confirming that TDP2 5' phosphodiesterase activity is required for efficient virus replication. Importantly, we show for the first time that polysomes can assemble efficiently on VPg-linked RNA after the initial round of translation in a cell culture model, but both positive and negative strand RNA production is impaired in the absence of TDP2 at mid-times of infection, indicating that the presence of VPg on the viral RNA affects a step in the replication cycle downstream of translation (e.g., RNA synthesis). In agreement with this conclusion, we found that double-stranded RNA production (a marker of viral RNA synthesis) is delayed in TDP2 KO RPE-1 cells. Moreover, we show that premature encapsidation of nascent, VPg-linked RNA is not responsible for the observed virus growth defect. Our studies provide the first lines of evidence to suggest that either negative- or positive-strand RNA synthesis (or both) is a likely candidate for the step that requires the removal of VPg from the RNA for an enterovirus infection to proceed efficiently.
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Affiliation(s)
- Autumn C. Holmes
- Department of Microbiology & Molecular Genetics and Center for Virus Research, University of California, Irvine, CA 92697, USA;
| | - Guido Zagnoli-Vieira
- Genome Damage and Stability Centre, University of Sussex, Falmer, Brighton BN1 9RQ, UK; (G.Z.-V.); (K.W.C.)
| | - Keith W. Caldecott
- Genome Damage and Stability Centre, University of Sussex, Falmer, Brighton BN1 9RQ, UK; (G.Z.-V.); (K.W.C.)
| | - Bert L. Semler
- Department of Microbiology & Molecular Genetics and Center for Virus Research, University of California, Irvine, CA 92697, USA;
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9
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Woodman A, Lee KM, Janissen R, Gong YN, Dekker NH, Shih SR, Cameron CE. Predicting Intraserotypic Recombination in Enterovirus 71. J Virol 2019; 93:e02057-18. [PMID: 30487277 PMCID: PMC6364027 DOI: 10.1128/jvi.02057-18] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Accepted: 11/19/2018] [Indexed: 01/07/2023] Open
Abstract
Enteroviruses are well known for their ability to cause neurological damage and paralysis. The model enterovirus is poliovirus (PV), the causative agent of poliomyelitis, a condition characterized by acute flaccid paralysis. A related virus, enterovirus 71 (EV-A71), causes similar clinical outcomes in recurrent outbreaks throughout Asia. Retrospective phylogenetic analysis has shown that recombination between circulating strains of EV-A71 produces the outbreak-associated strains which exhibit increased virulence and/or transmissibility. While studies on the mechanism(s) of recombination in PV are ongoing in several laboratories, little is known about factors that influence recombination in EV-A71. We have developed a cell-based assay to study recombination of EV-A71 based upon previously reported assays for poliovirus recombination. Our results show that (i) EV-A71 strain type and RNA sequence diversity impacts recombination frequency in a predictable manner that mimics the observations found in nature; (ii) recombination is primarily a replicative process mediated by the RNA-dependent RNA polymerase; (iii) a mutation shown to reduce recombination in PV (L420A) similarly reduces EV-A71 recombination, suggesting conservation in mechanism(s); and (iv) sequencing of intraserotypic recombinant genomes indicates that template switching occurs by a mechanism that may require some sequence homology at the recombination junction and that the triggers for template switching may be sequence independent. The development of this recombination assay will permit further investigation on the interplay between replication, recombination and disease.IMPORTANCE Recombination is a mechanism that contributes to genetic diversity. We describe the first assay to study EV-A71 recombination. Results from this assay mimic what is observed in nature and can be used by others to predict future recombination events within the enterovirus species A group. In addition, our results highlight the central role played by the viral RNA-dependent RNA polymerase (RdRp) in the recombination process. Further, our results show that changes to a conserved residue in the RdRp from different species groups have a similar impact on viable recombinant virus yields, which is indicative of conservation in mechanism.
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Affiliation(s)
- Andrew Woodman
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania, USA
| | - Kuo-Ming Lee
- Research Center for Emerging Viral Infections, Chang Gung University, Taoyuan, Taiwan
| | - Richard Janissen
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Delft, The Netherlands
| | - Yu-Nong Gong
- Research Center for Emerging Viral Infections, Chang Gung University, Taoyuan, Taiwan
| | - Nynke H Dekker
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Delft, The Netherlands
| | - Shin-Ru Shih
- Research Center for Emerging Viral Infections, Chang Gung University, Taoyuan, Taiwan
- Department of Medical Biotechnology and Laboratory Science, College of Medicine, Chang Gung University, Taoyuan, Taiwan
- Department of Laboratory Medicine, Linkou Chang Gung Memorial Hospital, Taoyuan, Taiwan
- Research Center for Chinese Herbal Medicine, Research Center for Food and Cosmetic Safety, and Graduate Institute of Health Industry Technology, College of Human Ecology, Chang Gung University of Science and Technology, Taoyuan, Taiwan
| | - Craig E Cameron
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania, USA
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Bentley K, Evans DJ. Mechanisms and consequences of positive-strand RNA virus recombination. J Gen Virol 2018; 99:1345-1356. [PMID: 30156526 DOI: 10.1099/jgv.0.001142] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Genetic recombination in positive-strand RNA viruses is a significant evolutionary mechanism that drives the creation of viral diversity by the formation of novel chimaeric genomes. The process and its consequences, for example the generation of viruses with novel phenotypes, has historically been studied by analysis of the end products. More recently, with an appreciation that there are both replicative and non-replicative mechanisms at work, and with new approaches and techniques to analyse intermediate products, the viral and cellular factors that influence the process are becoming understood. The major influence on replicative recombination is the fidelity of viral polymerase, although RNA structures and sequences may also have an impact. In replicative recombination the viral polymerase is necessary and sufficient, although roles for other viral or cellular proteins may exist. In contrast, non-replicative recombination appears to be mediated solely by cellular components. Despite these insights, the relative importance of replicative and non-replicative mechanisms is not clear. Using single-stranded positive-sense RNA viruses as exemplars, we review the current state of understanding of the processes and consequences of recombination.
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Affiliation(s)
- Kirsten Bentley
- Biomedical Sciences Research Complex and School of Biology, University of St Andrews, St Andrews, UK
| | - David J Evans
- Biomedical Sciences Research Complex and School of Biology, University of St Andrews, St Andrews, UK
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Abstract
Reproduction of RNA viruses is typically error-prone due to the infidelity of their replicative machinery and the usual lack of proofreading mechanisms. The error rates may be close to those that kill the virus. Consequently, populations of RNA viruses are represented by heterogeneous sets of genomes with various levels of fitness. This is especially consequential when viruses encounter various bottlenecks and new infections are initiated by a single or few deviating genomes. Nevertheless, RNA viruses are able to maintain their identity by conservation of major functional elements. This conservatism stems from genetic robustness or mutational tolerance, which is largely due to the functional degeneracy of many protein and RNA elements as well as to negative selection. Another relevant mechanism is the capacity to restore fitness after genetic damages, also based on replicative infidelity. Conversely, error-prone replication is a major tool that ensures viral evolvability. The potential for changes in debilitated genomes is much higher in small populations, because in the absence of stronger competitors low-fit genomes have a choice of various trajectories to wander along fitness landscapes. Thus, low-fit populations are inherently unstable, and it may be said that to run ahead it is useful to stumble. In this report, focusing on picornaviruses and also considering data from other RNA viruses, we review the biological relevance and mechanisms of various alterations of viral RNA genomes as well as pathways and mechanisms of rehabilitation after loss of fitness. The relationships among mutational robustness, resilience, and evolvability of viral RNA genomes are discussed.
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Both cis and trans Activities of Foot-and-Mouth Disease Virus 3D Polymerase Are Essential for Viral RNA Replication. J Virol 2016; 90:6864-6883. [PMID: 27194768 PMCID: PMC4944275 DOI: 10.1128/jvi.00469-16] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Accepted: 05/11/2016] [Indexed: 11/20/2022] Open
Abstract
The Picornaviridae is a large family of positive-sense RNA viruses that contains numerous human and animal pathogens, including foot-and-mouth disease virus (FMDV). The picornavirus replication complex comprises a coordinated network of protein-protein and protein-RNA interactions involving multiple viral and host-cellular factors. Many of the proteins within the complex possess multiple roles in viral RNA replication, some of which can be provided in trans (i.e., via expression from a separate RNA molecule), while others are required in cis (i.e., expressed from the template RNA molecule). In vitro studies have suggested that multiple copies of the RNA-dependent RNA polymerase (RdRp) 3D are involved in the viral replication complex. However, it is not clear whether all these molecules are catalytically active or what other function(s) they provide. In this study, we aimed to distinguish between catalytically active 3D molecules and those that build a replication complex. We report a novel nonenzymatic cis-acting function of 3D that is essential for viral-genome replication. Using an FMDV replicon in complementation experiments, our data demonstrate that this cis-acting role of 3D is distinct from the catalytic activity, which is predominantly trans acting. Immunofluorescence studies suggest that both cis- and trans-acting 3D molecules localize to the same cellular compartment. However, our genetic and structural data suggest that 3D interacts in cis with RNA stem-loops that are essential for viral RNA replication. This study identifies a previously undescribed aspect of picornavirus replication complex structure-function and an important methodology for probing such interactions further. IMPORTANCE Foot-and-mouth disease virus (FMDV) is an important animal pathogen responsible for foot-and-mouth disease. The disease is endemic in many parts of the world with outbreaks within livestock resulting in major economic losses. Propagation of the viral genome occurs within replication complexes, and understanding this process can facilitate the development of novel therapeutic strategies. Many of the nonstructural proteins involved in replication possess multiple functions in the viral life cycle, some of which can be supplied to the replication complex from a separate genome (i.e., in trans) while others must originate from the template (i.e., in cis). Here, we present an analysis of cis and trans activities of the RNA-dependent RNA polymerase 3D. We demonstrate a novel cis-acting role of 3D in replication. Our data suggest that this role is distinct from its enzymatic functions and requires interaction with the viral genome. Our data further the understanding of genome replication of this important pathogen.
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Woodman A, Arnold JJ, Cameron CE, Evans DJ. Biochemical and genetic analysis of the role of the viral polymerase in enterovirus recombination. Nucleic Acids Res 2016; 44:6883-95. [PMID: 27317698 PMCID: PMC5001610 DOI: 10.1093/nar/gkw567] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Accepted: 06/14/2016] [Indexed: 11/13/2022] Open
Abstract
Genetic recombination in single-strand, positive-sense RNA viruses is a poorly understand mechanism responsible for generating extensive genetic change and novel phenotypes. By moving a critical cis-acting replication element (CRE) from the polyprotein coding region to the 3′ non-coding region we have further developed a cell-based assay (the 3′CRE-REP assay) to yield recombinants throughout the non-structural coding region of poliovirus from dually transfected cells. We have additionally developed a defined biochemical assay in which the only protein present is the poliovirus RNA dependent RNA polymerase (RdRp), which recapitulates the strand transfer events of the recombination process. We have used both assays to investigate the role of the polymerase fidelity and nucleotide turnover rates in recombination. Our results, of both poliovirus intertypic and intratypic recombination in the CRE-REP assay and using a range of polymerase variants in the biochemical assay, demonstrate that RdRp fidelity is a fundamental determinant of recombination frequency. High fidelity polymerases exhibit reduced recombination and low fidelity polymerases exhibit increased recombination in both assays. These studies provide the basis for the analysis of poliovirus recombination throughout the non-structural region of the virus genome and provide a defined biochemical assay to further dissect this important evolutionary process.
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Affiliation(s)
- Andrew Woodman
- Dept. of Biochemistry & Molecular Biology, 201 Althouse Lab, University Park, PA 16802, USA
| | - Jamie J Arnold
- Dept. of Biochemistry & Molecular Biology, 201 Althouse Lab, University Park, PA 16802, USA
| | - Craig E Cameron
- Dept. of Biochemistry & Molecular Biology, 201 Althouse Lab, University Park, PA 16802, USA
| | - David J Evans
- Biomedical Sciences Research Complex, North Haugh, University of St. Andrews, St. Andrews KY16 9ST, UK
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14
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Smithee S, Tracy S, Chapman NM. Reversion to wildtype of a mutated and nonfunctional coxsackievirus B3CRE(2C). Virus Res 2016; 220:136-49. [PMID: 27130630 DOI: 10.1016/j.virusres.2016.04.016] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Revised: 04/15/2016] [Accepted: 04/18/2016] [Indexed: 11/25/2022]
Abstract
The cis-acting replication element (CRE) in the 2C protein coding region [CRE(2C)] of enteroviruses (EV) facilitates the addition of two uridine residues (uridylylation) onto the virus-encoded protein VPg in order for it to serve as the RNA replication primer. We demonstrated that coxsackievirus B3 (CVB3) is replication competent in the absence of a native (uridylylating) CRE(2C) and also demonstrated that lack of a functional CRE(2C) led to generation of 5' terminal genomic deletions in the CVB3 CRE-knock-out (CVB3-CKO) population. We asked whether reversion of the mutated CRE(2C) occurred, thus permitting sustained replication, and when were 5' terminal deletions generated during replication. Virions were isolated from HeLa cells previously electroporated with infectious CVB3-CKO T7 transcribed RNA or from hearts and spleens of mice after transfection with CVB3-CKO RNA. Viral RNA was isolated in order to amplify the CRE(2C) coding region and the genomic 5' terminal sequences. Sequence analysis revealed reversion of the CVB3-CKO sequence to wildtype occurs by 8 days post-electroporation of HeLa cells and by 20days post-transfection in mice. However, 5' terminal deletions evolve prior to these times. Reversion of the CRE(2C) mutations to wildtype despite loss of the genomic 5' termini is consistent with the hypothesis that an intact CRE(2C) is inherently vital to EV replication even when it is not enabling efficient positive strand initiation.
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Affiliation(s)
- Shane Smithee
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, NE, USA; Centers for Disease Control and Prevention, 1600 Clifton Road, Atlanta, GA 30033, USA
| | - Steven Tracy
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, NE, USA
| | - Nora M Chapman
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, NE, USA.
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15
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Mutational Disruption of cis-Acting Replication Element 2C in Coxsackievirus B3 Leads to 5'-Terminal Genomic Deletions. J Virol 2015; 89:11761-72. [PMID: 26355088 PMCID: PMC4645312 DOI: 10.1128/jvi.01308-15] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2015] [Accepted: 09/01/2015] [Indexed: 12/14/2022] Open
Abstract
UNLABELLED Following natural human or experimental murine infections and in cell culture, coxsackievirus B (CVB) RNA can persist for weeks in the absence of a cytopathic effect, yet viral RNA remains detectable. Our earlier studies demonstrated that this persistence produced viral RNA with up to 49 nucleotide deletions at the genomic 5' terminus which partially degraded the cloverleaf (or domain I), an RNA structure required for efficient viral replication. A cis-acting replication element (CRE) in the 2C protein-coding region [CRE(2C)] templates the addition of two uridine residues to the virus genome-encoded RNA replication primer VPg prior to positive-strand synthesis. Because our previous work also demonstrated that the genomes of CVB with a 5'-terminal deletion (CVB-TD) have VPg covalently linked, even though they rarely terminate in the canonical UU donated by CRE(2C)-mediated uridylylation of VPg, we hypothesized that a functional (uridylylating) CRE(2C) would be unnecessary for CVB-TD replication. Using the same 16 mutations in the CVB3 CRE(2C) structure that were considered lethal for this virus by others, we demonstrate here both in infected cell cultures and in mice that wild-type (wt) and CVB3-TD strains carrying these mutations with a nonuridylylating CRE(2C) are viable. While the wt genome with the mutated CRE(2C) displays suppressed replication levels similar to those observed in a CVB3-TD strain, mutation of the CRE(2C) function in a CVB3-TD strain does not further decrease replication. Finally, we show that replication of the parental CVB3 strain containing the mutated CRE(2C) drives the de novo generation of genomic deletions at the 5' terminus. IMPORTANCE In this report, we demonstrate that while CVB can replicate without a uridylylating CRE(2C), the replication rate suffers significantly. Further, deletions at the 5' terminus of the genome are generated in this virus population, with this virus population supplanting the wild-type population. This demonstrates that VPg can prime without being specifically uridylylated and that this priming is error prone, resulting in the loss of sequence information from the 5' terminus. These findings have significance when considering the replication of human enteroviruses, and we believe that these data are unattainable in a cell-free system due to the poor replication of these CRE-deficient viruses.
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Paul AV, Wimmer E. Initiation of protein-primed picornavirus RNA synthesis. Virus Res 2015; 206:12-26. [PMID: 25592245 DOI: 10.1016/j.virusres.2014.12.028] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Revised: 12/16/2014] [Accepted: 12/24/2014] [Indexed: 12/14/2022]
Abstract
Plus strand RNA viruses use different mechanisms to initiate the synthesis of their RNA chains. The Picornaviridae family constitutes a large group of plus strand RNA viruses that possess a small terminal protein (VPg) covalently linked to the 5'-end of their genomes. The RNA polymerases of these viruses use VPg as primer for both minus and plus strand RNA synthesis. In the first step of the initiation reaction the RNA polymerase links a UMP to the hydroxyl group of a tyrosine in VPg using as template a cis-replicating element (cre) positioned in different regions of the viral genome. In this review we will summarize what is known about the initiation reaction of protein-primed RNA synthesis by the RNA polymerases of the Picornaviridae. As an example we will use the RNA polymerase of poliovirus, the prototype of Picornaviridae. We will also discuss models of how these nucleotidylylated protein primers might be used, together with viral and cellular replication proteins and other cis-replicating RNA elements, during minus and plus strand RNA synthesis.
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Affiliation(s)
- Aniko V Paul
- Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, NY 11790, United States.
| | - Eckard Wimmer
- Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, NY 11790, United States
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Kempf BJ, Barton DJ. Picornavirus RNA polyadenylation by 3D(pol), the viral RNA-dependent RNA polymerase. Virus Res 2015; 206:3-11. [PMID: 25559071 PMCID: PMC4801031 DOI: 10.1016/j.virusres.2014.12.030] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2014] [Revised: 12/15/2014] [Accepted: 12/24/2014] [Indexed: 11/06/2022]
Abstract
Picornaviral RdRPs are responsible for the polyadenylation of viral RNA. Reiterative transcription mechanisms occur during replication of poly(A) tails. Conserved RdRP structures influence the size of poly(A) tails. Common features of picornavirus RdRPs and telomerase reverse transcriptase. Poly(A) tails are a telomere of picornavirus RNA genomes.
Poly(A) tails are functionally important features of all picornavirus RNA genomes. Some viruses have genomes with relatively short poly(A) tails (encephalomyocarditis virus) whereas others have genomes with longer poly(A) tails (polioviruses and rhinoviruses). Here we review the polyadenylation of picornavirus RNA as it relates to the structure and function of 3Dpol. Poliovirus 3Dpol uses template-dependent reiterative transcription mechanisms as it replicates the poly(A) tails of viral RNA (Steil et al., 2010). These mechanisms are analogous to those involved in the polyadenylation of vesicular stomatitis virus and influenza virus mRNAs. 3Dpol residues intimately associated with viral RNA templates and products regulate the size of poly(A) tails in viral RNA (Kempf et al., 2013). Consistent with their ancient evolutionary origins, picornavirus 3Dpol and telomerase reverse transcriptase (TERT) share structural and functional features. Structurally, both 3Dpol and TERT assume a “right-hand” conformation with thumb, palm and fingers domains encircling templates and products. Functionally, both 3Dpol and TERT use template-dependent reiterative transcription mechanisms to synthesize repetitive sequences: poly(A) tails in the case of picornavirus RNA genomes and DNA telomeres in the case of eukaryotic chromosomes. Thus, picornaviruses and their eukaryotic hosts (humans and animals) maintain the 3′ ends of their respective genomes via evolutionarily related mechanisms.
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Affiliation(s)
- Brian J Kempf
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, CO 80045, United States
| | - David J Barton
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, CO 80045, United States.
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Son KY, Kim DS, Kwon J, Choi JS, Kang MI, Belsham GJ, Cho KO. Full-length genomic analysis of Korean porcine Sapelovirus strains. PLoS One 2014; 9:e107860. [PMID: 25229940 PMCID: PMC4168140 DOI: 10.1371/journal.pone.0107860] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2014] [Accepted: 08/07/2014] [Indexed: 12/17/2022] Open
Abstract
Porcine sapelovirus (PSV), a species of the genus Sapelovirus within the family Picornaviridae, is associated with diarrhea, pneumonia, severe neurological disorders, and reproductive failure in pigs. However, the structural features of the complete PSV genome remain largely unknown. To analyze the structural features of PSV genomes, the full-length nucleotide sequences of three Korean PSV strains were determined and analyzed using bioinformatic techniques in comparison with other known PSV strains. The Korean PSV genomes ranged from 7,542 to 7,566 nucleotides excluding the 3′ poly(A) tail, and showed the typical picornavirus genome organization; 5′untranslated region (UTR)-L-VP4-VP2-VP3-VP1-2A-2B-2C-3A-3B-3C-3D-3′UTR. Three distinct cis-active RNA elements, the internal ribosome entry site (IRES) in the 5′UTR, a cis-replication element (CRE) in the 2C coding region and 3′UTR were identified and their structures were predicted. Interestingly, the structural features of the CRE and 3′UTR were different between PSV strains. The availability of these first complete genome sequences for PSV strains will facilitate future investigations of the molecular pathogenesis and evolutionary characteristics of PSV.
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Affiliation(s)
- Kyu-Yeol Son
- Laboratory of Veterinary Pathology, College of Veterinary Medicine, Chonnam National University, Gwangju, Republic of Korea
| | - Deok-Song Kim
- Laboratory of Veterinary Pathology, College of Veterinary Medicine, Chonnam National University, Gwangju, Republic of Korea
| | - Joseph Kwon
- Division of Life Science, Korea Basic Science Institute, Yuseong-gu, Daejeon, Republic of Korea
| | - Jong-Soon Choi
- Division of Life Science, Korea Basic Science Institute, Yuseong-gu, Daejeon, Republic of Korea
| | - Mun-Il Kang
- Laboratory of Veterinary Pathology, College of Veterinary Medicine, Chonnam National University, Gwangju, Republic of Korea
| | - Graham J. Belsham
- National Veterinary Institute, Technical University of Denmark, Kalvehave, Denmark
- * E-mail: (GJB); (KOC)
| | - Kyoung-Oh Cho
- Laboratory of Veterinary Pathology, College of Veterinary Medicine, Chonnam National University, Gwangju, Republic of Korea
- * E-mail: (GJB); (KOC)
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Lowry K, Woodman A, Cook J, Evans DJ. Recombination in enteroviruses is a biphasic replicative process involving the generation of greater-than genome length 'imprecise' intermediates. PLoS Pathog 2014; 10:e1004191. [PMID: 24945141 PMCID: PMC4055744 DOI: 10.1371/journal.ppat.1004191] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2013] [Accepted: 05/02/2014] [Indexed: 01/29/2023] Open
Abstract
Recombination in enteroviruses provides an evolutionary mechanism for acquiring extensive regions of novel sequence, is suggested to have a role in genotype diversity and is known to have been key to the emergence of novel neuropathogenic variants of poliovirus. Despite the importance of this evolutionary mechanism, the recombination process remains relatively poorly understood. We investigated heterologous recombination using a novel reverse genetic approach that resulted in the isolation of intermediate chimeric intertypic polioviruses bearing genomes with extensive duplicated sequences at the recombination junction. Serial passage of viruses exhibiting such imprecise junctions yielded progeny with increased fitness which had lost the duplicated sequences. Mutations or inhibitors that changed polymerase fidelity or the coalescence of replication complexes markedly altered the yield of recombinants (but did not influence non-replicative recombination) indicating both that the process is replicative and that it may be possible to enhance or reduce recombination-mediated viral evolution if required. We propose that extant recombinants result from a biphasic process in which an initial recombination event is followed by a process of resolution, deleting extraneous sequences and optimizing viral fitness. This process has implications for our wider understanding of ‘evolution by duplication’ in the positive-strand RNA viruses. The rapid evolution of most positive-sense RNA viruses enables them to escape immune surveillance and adapt to new hosts. Genetic variation arises due to their error-prone RNA polymerases and by recombination of viral genomes in co-infected cells. We have developed a novel approach to analyse the poorly understood mechanism of recombination using a poliovirus model system. We characterised the initial viable recombinants and demonstrate the majority are longer than genome length due to an imprecise crossover event that duplicates part of the genome. These viruses are unfit, but rapidly lose the duplicated material and regain full fitness upon serial passage, a process we term resolution. We show this is a replicative recombination process by modifying the fidelity of the viral polymerase, or replication complex coalescence, using methods that have no influence on a previously reported, less efficient, non-replicative recombination mechanism. We conclude that recombination is a biphasic process involving separate generation and resolution events. These new insights into an important evolutionary mechanism have implications for our understanding of virus evolution through partial genome duplication, they suggest ways in which recombination might be modified and provides an approach that may be exploited to analyse recombination in other RNA viruses.
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Affiliation(s)
- Kym Lowry
- School of Life Sciences, University of Warwick, Coventry, United Kingdom
| | - Andrew Woodman
- School of Life Sciences, University of Warwick, Coventry, United Kingdom
| | - Jonathan Cook
- School of Life Sciences, University of Warwick, Coventry, United Kingdom
| | - David J. Evans
- School of Life Sciences, University of Warwick, Coventry, United Kingdom
- * E-mail:
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Tapparel C, Siegrist F, Petty TJ, Kaiser L. Picornavirus and enterovirus diversity with associated human diseases. INFECTION GENETICS AND EVOLUTION 2012. [PMID: 23201849 DOI: 10.1016/j.meegid.2012.10.016] [Citation(s) in RCA: 334] [Impact Index Per Article: 25.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Members of the Picornaviridae family are non-enveloped, positive-stranded RNA viruses with a 30nm icosahedral capsid. This virus family exhibits a considerable amount of genetic variability driven both by mutation and recombination. Recently, three previously unknown human picornaviruses, namely the human Saffold cardiovirus, cosavirus and salivirus, have been identified in stools or respiratory samples from subjects presenting symptoms ranging from gastroenteritis to acute flaccid paralysis. However, these viruses were also frequently detected in asymptomatic subjects and their clinical relevance remains to be elucidated. The Enterovirus genus is a prototype example of the Picornaviridae heterogeneity at both genetic and phenotypic levels. This genus is divided into 10 species, seven of which contain human viruses, including three Rhinovirus species. Both human rhino- and enteroviruses are also characterized by high levels of genetic variability, as exemplified by the existence of over 250 different serotypes and the recent discovery of new enterovirus genotypes and the Rhinovirus C species. Despite their common genomic features, rhinoviruses are restricted to the respiratory tract, whereas the vast majority of enteroviruses infect the gastrointestinal tract and can spread to other organs, such as the heart or the central nervous system. Understanding the genetic determinants of such phenotypic diversity is an important challenge and a field for future investigation. Better characterization of these ubiquitous human pathogens may help to develop vaccines or antiviral treatments and to monitor the emergence of new strains.
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Affiliation(s)
- Caroline Tapparel
- Laboratory of Virology, Division of Infectious Diseases and Division of Laboratory Medicine, University of Geneva Hospitals, 4 Rue Gabrielle-Perret-Gentil, 1211 Geneva 14, Switzerland.
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21
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Abstract
The genomic RNA of poliovirus and closely related picornaviruses perform template and non-template functions during viral RNA replication. The non-template functions are mediated by cis-active RNA sequences that bind viral and cellular proteins to form RNP complexes. The RNP complexes mediate temporally dynamic, long-range interactions in the viral genome and ensure the specificity of replication. The 5' cloverleaf (5' CL)-RNP complex serves as a key cis-active element in all of the non-template functions of viral RNA. The 5'CL-RNP complex is proposed to interact with the cre-RNP complex during VPgpUpU synthesis, the 3'NTR-poly(A) RNP complex during negative-strand initiation and the 30 end negative-strand-RNP complex during positive-strand initiation. Co-ordinating these long-range interactions is important in regulating each step in the replication cycle.
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Affiliation(s)
- Sushma A Ogram
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, FL 32610, United States
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22
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Goodfellow I. The genome-linked protein VPg of vertebrate viruses - a multifaceted protein. Curr Opin Virol 2011; 1:355-62. [PMID: 22440837 DOI: 10.1016/j.coviro.2011.09.003] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2011] [Accepted: 09/20/2011] [Indexed: 12/24/2022]
Abstract
Several vertebrate positive-sense RNA viruses, namely the Picornaviridae and Caliciviridae have evolved to use a protein-primed mechanism of genome replication. This results in the covalent linkage of a virus encoded protein, VPg (viral protein genome-linked), to the 5' end of viral RNA. Recent studies have highlighted the pivotal role VPg plays in the life cycle of these viruses, which in the case of the Caliciviridae, includes a role in viral protein synthesis. This article provides an overview of the current knowledge of the functions of vertebrate RNA virus VPg proteins, illustrating their diverse function and the parallels they share with plant virus VPg proteins.
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Affiliation(s)
- Ian Goodfellow
- Section of Virology, Department of Medicine, Imperial College London, London, United Kingdom
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23
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Abstract
Amiloride and its derivative 5-(N-ethyl-N-isopropyl)amiloride (EIPA) were previously shown to inhibit coxsackievirus B3 (CVB3) RNA replication in cell culture, with two amino acid substitutions in the viral RNA-dependent RNA polymerase 3D(pol) conferring partial resistance of CVB3 to these compounds (D. N. Harrison, E. V. Gazina, D. F. Purcell, D. A. Anderson, and S. Petrou, J. Virol. 82:1465-1473, 2008). Here we demonstrate that amiloride and EIPA inhibit the enzymatic activity of CVB3 3D(pol) in vitro, affecting both VPg uridylylation and RNA elongation. Examination of the mechanism of inhibition of 3D(pol) by amiloride showed that the compound acts as a competitive inhibitor, competing with incoming nucleoside triphosphates (NTPs) and Mg(2+). Docking analysis suggested a binding site for amiloride and EIPA in 3D(pol), located in close proximity to one of the Mg(2+) ions and overlapping the nucleotide binding site, thus explaining the observed competition. This is the first report of a molecular mechanism of action of nonnucleoside inhibitors against a picornaviral RNA-dependent RNA polymerase.
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24
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Vogt DA, Andino R. An RNA element at the 5'-end of the poliovirus genome functions as a general promoter for RNA synthesis. PLoS Pathog 2010; 6:e1000936. [PMID: 20532207 PMCID: PMC2880563 DOI: 10.1371/journal.ppat.1000936] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2010] [Accepted: 05/03/2010] [Indexed: 12/28/2022] Open
Abstract
RNA structures present throughout RNA virus genomes serve as scaffolds to organize multiple factors involved in the initiation of RNA synthesis. Several of these RNA elements play multiple roles in the RNA replication pathway. An RNA structure formed around the 5'- end of the poliovirus genomic RNA has been implicated in the initiation of both negative- and positive-strand RNA synthesis. Dissecting the roles of these multifunctional elements is usually hindered by the interdependent nature of the viral replication processes and often pleiotropic effects of mutations. Here, we describe a novel approach to examine RNA elements with multiple roles. Our approach relies on the duplication of the RNA structure so that one copy is dedicated to the initiation of negative-strand RNA synthesis, while the other mediates positive-strand synthesis. This allows us to study the function of the element in promoting positive-strand RNA synthesis, independently of its function in negative-strand initiation. Using this approach, we demonstrate that the entire 5'-end RNA structure that forms on the positive-strand is required for initiation of new positive-strand RNAs. Also required to initiate positive-strand RNA synthesis are the binding sites for the viral polymerase precursor, 3CD, and the host factor, PCBP. Furthermore, we identify specific nucleotide sequences within "stem a" that are essential for the initiation of positive-strand RNA synthesis. These findings provide direct evidence for a trans-initiation model, in which binding of proteins to internal sequences of a pre-existing positive-strand RNA affects the synthesis of subsequent copies of that RNA, most likely by organizing replication factors around the initiation site.
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Affiliation(s)
- Dorothee A. Vogt
- Department of Microbiology and Immunology, University of California, San Francisco, California, United States of America
| | - Raul Andino
- Department of Microbiology and Immunology, University of California, San Francisco, California, United States of America
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25
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Conversion of VPg into VPgpUpUOH before and during poliovirus negative-strand RNA synthesis. J Virol 2009; 83:12660-70. [PMID: 19812161 DOI: 10.1128/jvi.01676-08] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
There are two protein primers involved in picornavirus RNA replication, VPg, the viral protein of the genome, and VPgpUpU(OH). A cis-acting replication element (CRE) within the open reading frame of poliovirus (PV) RNA allows the viral RNA-dependent RNA polymerase 3D(Pol) to catalyze the conversion of VPg into VPgpUpU(OH). In this study, we used preinitiation RNA replication complexes (PIRCs) to determine when CRE-dependent VPg uridylylation occurs relative to the sequential synthesis of negative- and positive-strand RNA. Guanidine HCl (2 mM), a reversible inhibitor of PV 2C(ATPase), prevented CRE-dependent VPgpUpU(OH) synthesis and the initiation of negative-strand RNA synthesis. VPgpUpU(OH) and nascent negative-strand RNA molecules were synthesized coincident in time following the removal of guanidine, consistent with PV RNA functioning simultaneously as a template for CRE-dependent VPgpUpU(OH) synthesis and negative-strand RNA synthesis. The amounts of [(32)P]UMP incorporated into VPgpUpU(OH) and negative-strand RNA products indicated that 100 to 400 VPgpUpU(OH) molecules were made coincident in time with each negative-strand RNA. 3'-dCTP inhibited the elongation of nascent negative-strand RNAs without affecting CRE-dependent VPg uridylylation. A 3' nontranslated region mutation which inhibited negative-strand RNA synthesis did not inhibit CRE-dependent VPg uridylylation. Together, the data implicate 2C(ATPase) in the mechanisms whereby PV RNA functions as a template for reiterative CRE-dependent VPg uridylylation before and during negative-strand RNA synthesis.
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Steil BP, Barton DJ. Cis-active RNA elements (CREs) and picornavirus RNA replication. Virus Res 2009; 139:240-52. [PMID: 18773930 PMCID: PMC2692539 DOI: 10.1016/j.virusres.2008.07.027] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2008] [Revised: 07/25/2008] [Accepted: 07/29/2008] [Indexed: 10/21/2022]
Abstract
Our understanding of picornavirus RNA replication has improved over the past 10 years, due in large part to the discovery of cis-active RNA elements (CREs) within picornavirus RNA genomes. CREs function as templates for the conversion of VPg, the Viral Protein of the genome, into VPgpUpU(OH). These so called CREs are different from the previously recognized cis-active RNA sequences and structures within the 5' and 3' NTRs of picornavirus genomes. Two adenosine residues in the loop of the CRE RNA structures allow the viral RNA-dependent RNA polymerase 3D(Pol) to add two uridine residues to the tyrosine residue of VPg. Because VPg and/or VPgpUpU(OH) prime the initiation of viral RNA replication, the asymmetric replication of viral RNA could not be explained without an understanding of the viral RNA template involved in the conversion of VPg into VPgpUpU(OH) primers. We review the growing body of knowledge regarding picornavirus CREs and discuss how CRE RNAs work coordinately with viral replication proteins and other cis-active RNAs in the 5' and 3' NTRs during RNA replication.
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Affiliation(s)
- Benjamin P Steil
- Department of Microbiology and Program in Molecular Biology, University of Colorado Denver, School of Medicine, United States
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Cordey S, Gerlach D, Junier T, Zdobnov EM, Kaiser L, Tapparel C. The cis-acting replication elements define human enterovirus and rhinovirus species. RNA (NEW YORK, N.Y.) 2008; 14:1568-1578. [PMID: 18541697 PMCID: PMC2491478 DOI: 10.1261/rna.1031408] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2008] [Accepted: 04/24/2008] [Indexed: 05/26/2023]
Abstract
Replication of picornaviruses is dependent on VPg uridylylation, which is linked to the presence of the internal cis-acting replication element (cre). Cre are located within the sequence encoding polyprotein, yet at distinct positions as demonstrated for poliovirus and coxsackievirus-B3, cardiovirus, and human rhinovirus (HRV-A and HRV-B), overlapping proteins 2C, VP2, 2A, and VP1, respectively. Here we report a novel distinct cre element located in the VP2 region of the recently reported HRV-A2 species and provide evolutionary evidence of its functionality. We also experimentally interrogated functionality of recently identified HRV-B cre in the 2C region that is orthologous to the human enterovirus (HEV) cre and show that it is dispensable for replication and appears to be a nonfunctional evolutionary relic. In addition, our mutational analysis highlights two amino acids in the 2C protein that are crucial for replication. Remarkably, we conclude that each genetic clade of HRV and HEV is characterized by a unique functional cre element, where evolutionary success of a new genetic lineage seems to be associated with an invention of a novel cre motif and decay of the ancestral one. Therefore, we propose that cre element could be considered as an additional criterion for human rhinovirus and enterovirus classification.
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Affiliation(s)
- Samuel Cordey
- Central Laboratory of Virology, Division of Infectious Diseases, University of Geneva Hospitals, 1211 Geneva 14, Switzerland.
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28
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Poliovirus cis-acting replication element-dependent VPg Uridylylation lowers the Km of the initiating nucleoside triphosphate for viral RNA replication. J Virol 2008; 82:9400-8. [PMID: 18653453 DOI: 10.1128/jvi.00427-08] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Initiation of RNA synthesis by RNA-dependent RNA polymerases occurs when a phosphodiester bond is formed between the first two nucleotides in the 5' terminus of product RNA. The concentration of initiating nucleoside triphosphates (NTPi) required for RNA synthesis is typically greater than the concentration of NTPs required for elongation. VPg, a small viral protein, is covalently attached to the 5' end of picornavirus negative- and positive-strand RNAs. A cis-acting replication element (CRE) within picornavirus RNAs serves as a template for the uridylylation of VPg, resulting in the synthesis of VPgpUpU(OH). Mutations within the CRE RNA structure prevent VPg uridylylation. While the tyrosine hydroxyl of VPg can prime negative-strand RNA synthesis in a CRE- and VPgpUpU(OH)-independent manner, CRE-dependent VPgpUpU(OH) synthesis is absolutely required for positive-strand RNA synthesis. As reported herein, low concentrations of UTP did not support negative-strand RNA synthesis when CRE-disrupting mutations prevented VPg uridylylation, whereas correspondingly low concentrations of CTP or GTP had no negative effects on the magnitude of CRE-independent negative-strand RNA synthesis. The experimental data indicate that CRE-dependent VPg uridylylation lowers the K(m) of UTP required for viral RNA replication and that CRE-dependent VPgpUpU(OH) synthesis was required for efficient negative-strand RNA synthesis, especially when UTP concentrations were limiting. By lowering the concentration of UTP needed for the initiation of RNA replication, CRE-dependent VPg uridylylation provides a mechanism for a more robust initiation of RNA replication.
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29
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The crystal structure of coxsackievirus B3 RNA-dependent RNA polymerase in complex with its protein primer VPg confirms the existence of a second VPg binding site on Picornaviridae polymerases. J Virol 2008; 82:9577-90. [PMID: 18632861 DOI: 10.1128/jvi.00631-08] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The RNA-dependent RNA polymerase (RdRp) is a central piece in the replication machinery of RNA viruses. In picornaviruses this essential RdRp activity also uridylates the VPg peptide, which then serves as a primer for RNA synthesis. Previous genetic, binding, and biochemical data have identified a VPg binding site on poliovirus RdRp and have shown that is was implicated in VPg uridylation. More recent structural studies have identified a topologically distinct site on the closely related foot-and-mouth disease virus RdRp supposed to be the actual VPg-primer-binding site. Here, we report the crystal structure at 2.5-A resolution of active coxsackievirus B3 RdRp (also named 3D(pol)) in a complex with VPg and a pyrophosphate. The pyrophosphate is situated in the active-site cavity, occupying a putative binding site either for the coproduct of the reaction or an incoming NTP. VPg is bound at the base of the thumb subdomain, providing first structural evidence for the VPg binding site previously identified by genetic and biochemical methods. The binding mode of VPg to CVB3 3D(pol) at this site excludes its uridylation by the carrier 3D(pol). We suggest that VPg at this position is either uridylated by another 3D(pol) molecule or that it plays a stabilizing role within the uridylation complex. The CVB3 3D(pol)/VPg complex structure is expected to contribute to the understanding of the multicomponent VPg-uridylation complex essential for the initiation of genome replication of picornaviruses.
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Svitkin YV, Costa-Mattioli M, Herdy B, Perreault S, Sonenberg N. Stimulation of picornavirus replication by the poly(A) tail in a cell-free extract is largely independent of the poly(A) binding protein (PABP). RNA (NEW YORK, N.Y.) 2007; 13:2330-2340. [PMID: 17942745 PMCID: PMC2080607 DOI: 10.1261/rna.606407] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2007] [Accepted: 08/21/2007] [Indexed: 05/25/2023]
Abstract
Picornavirus infectivity is dependent on the RNA poly(A) tail, which binds the poly(A) binding protein (PABP). PABP was reported to stimulate viral translation and RNA synthesis. Here, we studied encephalomyocarditis virus (EMCV) and poliovirus (PV) genome expression in Krebs-2 and HeLa cell-free extracts that were drastically depleted of PABP (96%-99%). Although PABP depletion markedly diminished EMCV and PV internal ribosome entry site (IRES)-mediated translation of a polyadenylated luciferase mRNA, it displayed either no (EMCV) or slight (PV) deleterious effect on the translation of the full-length viral RNAs. Moreover, PABP-depleted extracts were fully competent in supporting EMCV and PV RNA replication and virus assembly. In contrast, removing the poly(A) tail from EMCV RNA dramatically reduced RNA synthesis and virus yields in cell-free reactions. The advantage conferred by the poly(A) tail to EMCV synthesis was more pronounced in untreated than in nuclease-treated extract, indicating that endogenous cellular mRNAs compete with the viral RNA for a component(s) of the RNA replication machinery. These results suggest that the poly(A) tail functions in picornavirus replication largely independent of PABP.
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Affiliation(s)
- Yuri V Svitkin
- Department of Biochemistry and McGill Cancer Centre, McGill University, Montreal, Quebec, Canada H3G 1Y6.
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Tapparel C, Junier T, Gerlach D, Cordey S, Van Belle S, Perrin L, Zdobnov EM, Kaiser L. New complete genome sequences of human rhinoviruses shed light on their phylogeny and genomic features. BMC Genomics 2007; 8:224. [PMID: 17623054 PMCID: PMC1949831 DOI: 10.1186/1471-2164-8-224] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2007] [Accepted: 07/10/2007] [Indexed: 12/15/2022] Open
Abstract
Background Human rhinoviruses (HRV), the most frequent cause of respiratory infections, include 99 different serotypes segregating into two species, A and B. Rhinoviruses share extensive genomic sequence similarity with enteroviruses and both are part of the picornavirus family. Nevertheless they differ significantly at the phenotypic level. The lack of HRV full-length genome sequences and the absence of analysis comparing picornaviruses at the whole genome level limit our knowledge of the genomic features supporting these differences. Results Here we report complete genome sequences of 12 HRV-A and HRV-B serotypes, more than doubling the current number of available HRV sequences. The whole-genome maximum-likelihood phylogenetic analysis suggests that HRV-B and human enteroviruses (HEV) diverged from the last common ancestor after their separation from HRV-A. On the other hand, compared to HEV, HRV-B are more related to HRV-A in the capsid and 3B-C regions. We also identified the presence of a 2C cis-acting replication element (cre) in HRV-B that is not present in HRV-A, and that had been previously characterized only in HEV. In contrast to HEV viruses, HRV-A and HRV-B share also markedly lower GC content along the whole genome length. Conclusion Our findings provide basis to speculate about both the biological similarities and the differences (e.g. tissue tropism, temperature adaptation or acid lability) of these three groups of viruses.
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Affiliation(s)
- Caroline Tapparel
- Central Laboratory of Virology, Division of Infectious Diseases, University of Geneva Hospitals, 24 Rue Micheli-du-Crest, 1211 Geneva 14, Switzerland
| | - Thomas Junier
- Department of Genetic Medicine and Development, University of Geneva Medical School, 1 Rue Michel-Servet, 1211 Geneva 14, Switzerland
| | - Daniel Gerlach
- Department of Genetic Medicine and Development, University of Geneva Medical School, 1 Rue Michel-Servet, 1211 Geneva 14, Switzerland
| | - Samuel Cordey
- Central Laboratory of Virology, Division of Infectious Diseases, University of Geneva Hospitals, 24 Rue Micheli-du-Crest, 1211 Geneva 14, Switzerland
| | - Sandra Van Belle
- Central Laboratory of Virology, Division of Infectious Diseases, University of Geneva Hospitals, 24 Rue Micheli-du-Crest, 1211 Geneva 14, Switzerland
| | - Luc Perrin
- Central Laboratory of Virology, Division of Infectious Diseases, University of Geneva Hospitals, 24 Rue Micheli-du-Crest, 1211 Geneva 14, Switzerland
| | - Evgeny M Zdobnov
- Department of Genetic Medicine and Development, University of Geneva Medical School, 1 Rue Michel-Servet, 1211 Geneva 14, Switzerland
- Swiss Institute of Bioinformatics, 1 Rue Michel-Servet, 1211 Geneva 14, Switzerland
- Imperial College London, South Kensington Campus, SW7 2AZ London, UK
| | - Laurent Kaiser
- Central Laboratory of Virology, Division of Infectious Diseases, University of Geneva Hospitals, 24 Rue Micheli-du-Crest, 1211 Geneva 14, Switzerland
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Pathak HB, Arnold JJ, Wiegand PN, Hargittai MRS, Cameron CE. Picornavirus genome replication: assembly and organization of the VPg uridylylation ribonucleoprotein (initiation) complex. J Biol Chem 2007; 282:16202-13. [PMID: 17392285 PMCID: PMC2116992 DOI: 10.1074/jbc.m610608200] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
All picornaviruses have a protein, VPg, covalently linked to the 5'-ends of their genomes. Uridylylated VPg (VPg-pUpU) is thought to serve as the protein primer for RNA synthesis. VPg-pUpU can be produced in vitro by the viral polymerase, 3Dpol, in a reaction in which a single adenylate residue of a stem-loop structure, termed oriI, templates processive incorporation of UMP into VPg by using a "slide-back" mechanism. This reaction is greatly stimulated by viral precursor protein 3CD or its processed derivative, 3C; both contain RNA-binding and protease activities. We show that the 3C domain encodes specificity for oriI, and the 3D domain enhances the overall affinity for oriI. Thus, 3C(D) stimulation exhibits an RNA length dependence. By using a minimal system to evaluate the mechanism of VPg uridylylation, we show that the active complex contains polymerase, oriI, and 3C(D) at stoichiometry of 1:1:2. Dimerization of 3C(D) is supported by physical and structural data. Polymerase recruitment to and retention in this complex require a protein-protein interaction between the polymerase and 3C(D). Physical and functional data for this interaction are provided for three picornaviruses. VPg association with this complex is weak, suggesting that formation of a complex containing all necessary components of the reaction is rate-limiting for the reaction. We suggest that assembly of this complex in vivo would be facilitated by use of precursor proteins instead of processed proteins. These data provide a glimpse into the organization of the ribonucleoprotein complex that catalyzes this key step in picornavirus genome replication.
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Affiliation(s)
- Harsh B Pathak
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, Pennsylvania 16802, USA
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Karakasiliotis I, Chaudhry Y, Roberts LO, Goodfellow IG. Feline calicivirus replication: requirement for polypyrimidine tract-binding protein is temperature-dependent. J Gen Virol 2006; 87:3339-3347. [PMID: 17030868 DOI: 10.1099/vir.0.82153-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
The interaction of host-cell nucleic acid-binding proteins with the genomes of positive-stranded RNA viruses is known to play a role in the translation and replication of many viruses. To date, however, the characterization of similar interactions with the genomes of members of the family Caliciviridae has been limited to in vitro binding analysis. In this study, Feline calicivirus (FCV) has been used as a model system to identify and characterize the role of host-cell factors that interact with the viral RNA. It was demonstrated that polypyrimidine tract-binding protein (PTB) interacts specifically with the 5' sequences of the FCV genomic and subgenomic RNAs. Using RNA interference it was shown that PTB is required for efficient FCV replication in a temperature-dependent manner. siRNA-mediated knockdown of PTB resulted in a 15- to 100-fold reduction in virus titre, as well as a concomitant reduction in viral RNA and protein synthesis at 32 degrees C. In addition, virus-induced cytopathic effect was significantly delayed as a result of an siRNA-mediated reduction in PTB levels. A role for PTB in the calicivirus life cycle was more apparent at temperatures above and below 37 degrees C, fitting with the hypothesis that PTB functions as an RNA chaperone, potentially aiding the folding of RNA into functional structures. This is the first functional demonstration of a host-cell protein interacting with a calicivirus RNA.
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Affiliation(s)
- Ioannis Karakasiliotis
- Department of Virology, Faculty of Medicine, Imperial College London, St Mary's Campus, Norfolk Place, London W2 1PG, UK
| | - Yasmin Chaudhry
- Department of Virology, Faculty of Medicine, Imperial College London, St Mary's Campus, Norfolk Place, London W2 1PG, UK
| | - Lisa O Roberts
- School of Biomedical and Molecular Sciences, University of Surrey, Guildford, Surrey GU2 7XH, UK
| | - Ian G Goodfellow
- Department of Virology, Faculty of Medicine, Imperial College London, St Mary's Campus, Norfolk Place, London W2 1PG, UK
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34
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Nayak A, Goodfellow IG, Woolaway KE, Birtley J, Curry S, Belsham GJ. Role of RNA structure and RNA binding activity of foot-and-mouth disease virus 3C protein in VPg uridylylation and virus replication. J Virol 2006; 80:9865-75. [PMID: 16973591 PMCID: PMC1617274 DOI: 10.1128/jvi.00561-06] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The uridylylation of the VPg peptide primer is the first stage in the replication of picornavirus RNA. This process can be achieved in vitro using purified components, including 3B (VPg) with the RNA dependent RNA polymerase (3Dpol), the precursor 3CD, and an RNA template containing the cre/bus. We show that certain RNA sequences within the foot-and-mouth disease virus (FMDV) 5' untranslated region but outside of the cre/bus can enhance VPg uridylylation activity. Furthermore, we have shown that the FMDV 3C protein alone can substitute for 3CD, albeit less efficiently. In addition, the VPg precursors, 3B(3)3C and 3B(123)3C, can function as substrates for uridylylation in the absence of added 3C or 3CD. Residues within the FMDV 3C protein involved in interaction with the cre/bus RNA have been identified and are located on the face of the protein opposite from the catalytic site. These residues within 3C are also essential for VPg uridylylation activity and efficient virus replication.
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Affiliation(s)
- Arabinda Nayak
- BBSRC Institute for Animal Health, Pirbright, Woking, Surrey GU24 0NF, United Kingdom
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35
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Richards OC, Spagnolo JF, Lyle JM, Vleck SE, Kuchta RD, Kirkegaard K. Intramolecular and intermolecular uridylylation by poliovirus RNA-dependent RNA polymerase. J Virol 2006; 80:7405-15. [PMID: 16840321 PMCID: PMC1563691 DOI: 10.1128/jvi.02533-05] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
The 22-amino-acid protein VPg can be uridylylated in solution by purified poliovirus 3D polymerase in a template-dependent reaction thought to mimic primer formation during RNA amplification in infected cells. In the cell, the template used for the reaction is a hairpin RNA termed 2C-cre and, possibly, the poly(A) at the 3' end of the viral genome. Here, we identify several additional substrates for uridylylation by poliovirus 3D polymerase. In the presence of a 15-nucleotide (nt) RNA template, the poliovirus polymerase uridylylates other polymerase molecules in an intermolecular reaction that occurs in a single step, as judged by the chirality of the resulting phosphodiester linkage. Phosphate chirality experiments also showed that VPg uridylylation can occur by a single step; therefore, there is no obligatory uridylylated intermediate in the formation of uridylylated VPg. Other poliovirus proteins that could be uridylylated by 3D polymerase in solution were viral 3CD and 3AB proteins. Strong effects of both RNA and protein ligands on the efficiency and the specificity of the uridylylation reaction were observed: uridylylation of 3D polymerase and 3CD protein was stimulated by the addition of viral protein 3AB, and, when the template was poly(A) instead of the 15-nt RNA, the uridylylation of 3D polymerase itself became intramolecular instead of intermolecular. Finally, an antiuridine antibody identified uridylylated viral 3D polymerase and 3CD protein, as well as a 65- to 70-kDa host protein, in lysates of virus-infected human cells.
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Affiliation(s)
- Oliver C Richards
- Department of Microbiology and Immunology, Stanford University School of Medicine, 299 Campus Drive, Stanford, CA 94305-5402, USA
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36
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van Ooij MJM, Polacek C, Glaudemans DHRF, Kuijpers J, van Kuppeveld FJM, Andino R, Agol VI, Melchers WJG. Polyadenylation of genomic RNA and initiation of antigenomic RNA in a positive-strand RNA virus are controlled by the same cis-element. Nucleic Acids Res 2006; 34:2953-65. [PMID: 16738134 PMCID: PMC1474053 DOI: 10.1093/nar/gkl349] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2006] [Revised: 03/28/2006] [Accepted: 04/19/2006] [Indexed: 01/16/2023] Open
Abstract
Genomes and antigenomes of many positive-strand RNA viruses contain 3'-poly(A) and 5'-poly(U) tracts, respectively, serving as mutual templates. Mechanism(s) controlling the length of these homopolymeric stretches are not well understood. Here, we show that in coxsackievirus B3 (CVB3) and three other enteroviruses the poly(A) tract is approximately 80-90 and the poly(U) tract is approximately 20 nt-long. Mutagenesis analysis indicate that the length of the CVB3 3'-poly(A) is determined by the oriR, a cis-element in the 3'-noncoding region of viral RNA. In contrast, while mutations of the oriR inhibit initiation of (-) RNA synthesis, they do not affect the 5'-poly(U) length. Poly(A)-lacking genomes are able to acquire genetically unstable AU-rich poly(A)-terminated 3'-tails, which may be generated by a mechanism distinct from the cognate viral RNA polyadenylation. The aberrant tails ensure only inefficient replication. The possibility of RNA replication independent of oriR and poly(A) demonstrate that highly debilitated viruses are able to survive by utilizing 'emergence', perhaps atavistic, mechanisms.
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Affiliation(s)
- Mark J. M. van Ooij
- Department of Medical Microbiology Nijmegen Center for Molecular Life Science, Radboud University Nijmegen Medical CentrePO Box 9101, 6500 HB Nijmegen, The Netherlands
- M.P. Chumakov Institute of Poliomyelitis and Viral Encephalitides, Russian Academy of Medical SciencesMoscow Region 142782, Russia
- Moscow State UniversityMoscow 119899, Russia
- University of California, San Francisco, Mission Bay Genentech Hall, UCSF Department of Microbiology600 16th Street, PO Box 2280, San Francisco, CA 94143, USA
| | - Charlotta Polacek
- University of California, San Francisco, Mission Bay Genentech Hall, UCSF Department of Microbiology600 16th Street, PO Box 2280, San Francisco, CA 94143, USA
| | - Dirk H. R. F. Glaudemans
- Department of Medical Microbiology Nijmegen Center for Molecular Life Science, Radboud University Nijmegen Medical CentrePO Box 9101, 6500 HB Nijmegen, The Netherlands
- M.P. Chumakov Institute of Poliomyelitis and Viral Encephalitides, Russian Academy of Medical SciencesMoscow Region 142782, Russia
- Moscow State UniversityMoscow 119899, Russia
- University of California, San Francisco, Mission Bay Genentech Hall, UCSF Department of Microbiology600 16th Street, PO Box 2280, San Francisco, CA 94143, USA
| | - Judith Kuijpers
- Department of Medical Microbiology Nijmegen Center for Molecular Life Science, Radboud University Nijmegen Medical CentrePO Box 9101, 6500 HB Nijmegen, The Netherlands
- M.P. Chumakov Institute of Poliomyelitis and Viral Encephalitides, Russian Academy of Medical SciencesMoscow Region 142782, Russia
- Moscow State UniversityMoscow 119899, Russia
- University of California, San Francisco, Mission Bay Genentech Hall, UCSF Department of Microbiology600 16th Street, PO Box 2280, San Francisco, CA 94143, USA
| | - Frank J. M. van Kuppeveld
- Department of Medical Microbiology Nijmegen Center for Molecular Life Science, Radboud University Nijmegen Medical CentrePO Box 9101, 6500 HB Nijmegen, The Netherlands
- M.P. Chumakov Institute of Poliomyelitis and Viral Encephalitides, Russian Academy of Medical SciencesMoscow Region 142782, Russia
- Moscow State UniversityMoscow 119899, Russia
- University of California, San Francisco, Mission Bay Genentech Hall, UCSF Department of Microbiology600 16th Street, PO Box 2280, San Francisco, CA 94143, USA
| | - Raul Andino
- University of California, San Francisco, Mission Bay Genentech Hall, UCSF Department of Microbiology600 16th Street, PO Box 2280, San Francisco, CA 94143, USA
| | - Vadim I. Agol
- M.P. Chumakov Institute of Poliomyelitis and Viral Encephalitides, Russian Academy of Medical SciencesMoscow Region 142782, Russia
- Moscow State UniversityMoscow 119899, Russia
| | - Willem J. G. Melchers
- To whom correspondence should be addressed. Tel: +31 24 3614356; Fax: +31 24 3540216;
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37
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van Ooij MJM, Vogt DA, Paul A, Castro C, Kuijpers J, van Kuppeveld FJM, Cameron CE, Wimmer E, Andino R, Melchers WJG. Structural and functional characterization of the coxsackievirus B3 CRE(2C): role of CRE(2C) in negative- and positive-strand RNA synthesis. J Gen Virol 2006; 87:103-113. [PMID: 16361422 DOI: 10.1099/vir.0.81297-0] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
A stem-loop element located within the 2C-coding region of the coxsackievirus B3 (CVB3) genome has been proposed to function as a cis-acting replication element (CRE). It is shown here that disruption of this structure indeed interfered with viral RNA replication in vivo and abolished uridylylation of VPg in vitro. Site-directed mutagenesis demonstrated that the previously proposed enteroviral CRE consensus loop sequence, R(1)NNNAAR(2)NNNNNNR(3), is also applicable to CVB3 CRE(2C) and that a positive correlation exists between the ability of CRE(2C) mutants to serve as template in the uridylylation reaction and the capacity of these mutants to support viral RNA replication. To further investigate the effects of the mutations on negative-strand RNA synthesis, an in vitro translation/replication system containing HeLa S10 cell extracts was used. Similar to the results observed for poliovirus and rhinovirus, it was found that a complete disruption of the CRE(2C) structure interfered with positive-strand RNA synthesis, but not with negative-strand synthesis. All CRE(2C) point mutants affecting the enteroviral CRE consensus loop, however, showed a marked decrease in efficiency to induce negative-strand synthesis. Moreover, a transition (A(5)G) regarding the first templating adenosine residue in the loop was even unable to initiate complementary negative-strand synthesis above detectable levels. Taken together, these results indicate that the CVB3 CRE(2C) is not only required for the initiation of positive-strand RNA synthesis, but also plays an essential role in the efficient initiation of negative-strand RNA synthesis, a conclusion that has not been reached previously by using the cell-free system.
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Affiliation(s)
- Mark J M van Ooij
- Radboud University Medical Centre Nijmegen, Nijmegen Centre for Molecular Life Science, Department of Medical Microbiology, PO Box 9101, 6500 HB Nijmegen, The Netherlands
| | - Dorothee A Vogt
- University of California, San Francisco, Mission Bay Genentech Hall, UCSF Department of Microbiology, 600 16th Street, PO Box 2280, San Francisco, CA 94143, USA
| | - Aniko Paul
- Department of Molecular Genetics and Microbiology, School of Medicine, Stony Brook University, Stony Brook, NY 11794, USA
| | - Christian Castro
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA 16802, USA
| | - Judith Kuijpers
- Radboud University Medical Centre Nijmegen, Nijmegen Centre for Molecular Life Science, Department of Medical Microbiology, PO Box 9101, 6500 HB Nijmegen, The Netherlands
| | - Frank J M van Kuppeveld
- Radboud University Medical Centre Nijmegen, Nijmegen Centre for Molecular Life Science, Department of Medical Microbiology, PO Box 9101, 6500 HB Nijmegen, The Netherlands
| | - Craig E Cameron
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA 16802, USA
| | - Eckard Wimmer
- Department of Molecular Genetics and Microbiology, School of Medicine, Stony Brook University, Stony Brook, NY 11794, USA
| | - Raul Andino
- University of California, San Francisco, Mission Bay Genentech Hall, UCSF Department of Microbiology, 600 16th Street, PO Box 2280, San Francisco, CA 94143, USA
| | - Willem J G Melchers
- Radboud University Medical Centre Nijmegen, Nijmegen Centre for Molecular Life Science, Department of Medical Microbiology, PO Box 9101, 6500 HB Nijmegen, The Netherlands
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Abstract
Replication of poliovirus RNA is accomplished by the error-prone viral RNA-dependent RNA polymerase and hence is accompanied by numerous mutations. In addition, genetic errors may be introduced by nonreplicative mechanisms. Resulting variability is manifested by point mutations and genomic rearrangements (e.g., deletions, insertions and recombination). After description of basic mechanisms underlying this variability, the review focuses on regularities of poliovirus evolution (mutation fixation) in tissue cultures, human organisms and populations.
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Affiliation(s)
- V I Agol
- M.P. Chumakov Institute of Poliomyelitis and Viral Encephalitides, Russian Academy of Medical Sciences, 142782, Russia.
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39
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Buenz EJ, Howe CL. Picornaviruses and cell death. Trends Microbiol 2005; 14:28-36. [PMID: 16337385 DOI: 10.1016/j.tim.2005.11.003] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2005] [Revised: 10/07/2005] [Accepted: 11/21/2005] [Indexed: 11/21/2022]
Abstract
Members of the picornavirus family, including poliovirus and foot-and-mouth disease virus, are widespread pathogens of humans and domestic animals. Recent global developments in the resurgence of poliovirus infection and in the control of foot-and-mouth disease infection highlight the problems caused by the ability of picornaviruses to alter the apoptotic machinery of host cells and establish persistent infections. Despite the medical, economic and social impact of this family of viruses, little information exists that integrates the mechanisms of cell death and damage induced by related family members. Fortunately, examination of the reported roles and functions of individual viral proteins from multiple picornaviruses makes it possible to surmise canonical functions for these proteins. This review analyzes the canonical function of picornavirus proteins involved in the alteration of apoptotic homeostasis in infected host cells.
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Affiliation(s)
- Eric J Buenz
- Molecular Neuroscience Program, Department of Neurology, Department of Neuroscience, RO_GU_04_12_NR, Mayo Clinic College of Medicine, 200 First Street SW, Rochester, MN 55905, USA
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Silvestri LS, Parilla JM, Morasco BJ, Ogram SA, Flanegan JB. Relationship between poliovirus negative-strand RNA synthesis and the length of the 3' poly(A) tail. Virology 2005; 345:509-19. [PMID: 16297425 DOI: 10.1016/j.virol.2005.10.019] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2005] [Revised: 10/07/2005] [Accepted: 10/18/2005] [Indexed: 10/25/2022]
Abstract
The precise relationship between the length of the 3' poly(A) tail and the replication and infectivity of poliovirus RNA was examined in this study. With both poly(A)(11) and poly(A)(12) RNAs, negative-strand synthesis was 1-3% of the level observed with poly(A)(80) RNA. In contrast, increasing the length of the poly(A) tail from (A)(12) to (A)(13) resulted in about a ten-fold increase in negative-strand synthesis. This increase continued with each successive increase in poly(A) tail length. With poly(A)(20) RNA, RNA synthesis approached the level observed with poly(A)(80) RNA. A similar relationship was observed between poly(A) tail length and the infectivity of the viral RNA. A replication model is described which suggests that viral RNA replication is dependent on a poly(A) tail that is long enough to bind poly(A) binding protein and to act as a template for VPg uridylylation and negative-strand initiation.
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Affiliation(s)
- Lynn S Silvestri
- Department of Biochemistry and Molecular Biology, University of Florida, College of Medicine, Gainesville, 32610-0245, USA
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Choi IR, Horken KM, Stenger DC, French R. An internal RNA element in the P3 cistron of Wheat streak mosaic virus revealed by synonymous mutations that affect both movement and replication. J Gen Virol 2005; 86:2605-2614. [PMID: 16099920 DOI: 10.1099/vir.0.81081-0] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Multiple synonymous substitution mutations in the Wheat streak mosaic virus P3 cistron did not affect translation in vitro but rendered the virus incapable of systemic infection. Multiple synonymous substitutions in the cylindrical inclusion cistron did not alter infectivity or in vitro translation. To assess replication and movement phenotypes, P3 mutations were placed in context with a GUS reporter gene. GUS activity measured in barley protoplasts 36 h post-transfection indicated that mutants with synonymous substitutions in P3 retained the ability to replicate at 22–80 % of wild-type levels. Almost no GUS activity was detected in protoplasts transfected with a P3 frame-shift mutant. Histochemical GUS assays conducted 3 days post-inoculation (p.i.) revealed genomes with multiple synonymous substitutions in P3, which were able to establish infection foci limited to small clusters of cells that increased in size only slightly by 5 days p.i. Infection foci produced by wild-type Wheat streak mosaic virus-expressing GUS were much larger at 3 days p.i. and had coalesced by 5 days p.i. No GUS activity was detected in plants inoculated with the frame-shift mutant bearing GUS. Three of four mutants, each with a single synonymous substitution in the 3′-proximal half of the P3 cistron, were wild-type with respect to systemic infectivity. A model RNA secondary structure obtained for the region was disrupted by the debilitating single mutation but not by the other three single mutations. Collectively, these results identify an internal RNA sequence element in the P3 cistron that affects both replication and movement of the viral genome.
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Affiliation(s)
- Il-Ryong Choi
- United States Department of Agriculture - Agricultural Research Service and Department of Plant Pathology, University of Nebraska, 344 Keim Hall, Lincoln, NE 68583, USA
| | - Kempton M Horken
- United States Department of Agriculture - Agricultural Research Service and Department of Plant Pathology, University of Nebraska, 344 Keim Hall, Lincoln, NE 68583, USA
| | - Drake C Stenger
- United States Department of Agriculture - Agricultural Research Service and Department of Plant Pathology, University of Nebraska, 344 Keim Hall, Lincoln, NE 68583, USA
| | - Roy French
- United States Department of Agriculture - Agricultural Research Service and Department of Plant Pathology, University of Nebraska, 344 Keim Hall, Lincoln, NE 68583, USA
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Nayak A, Goodfellow IG, Belsham GJ. Factors required for the Uridylylation of the foot-and-mouth disease virus 3B1, 3B2, and 3B3 peptides by the RNA-dependent RNA polymerase (3Dpol) in vitro. J Virol 2005; 79:7698-706. [PMID: 15919922 PMCID: PMC1143669 DOI: 10.1128/jvi.79.12.7698-7706.2005] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
The 5' terminus of picornavirus genomic RNA is covalently linked to the virus-encoded peptide 3B (VPg). Foot-and-mouth disease virus (FMDV) is unique in encoding and using 3 distinct forms of this peptide. These peptides each act as primers for RNA synthesis by the virus-encoded RNA polymerase 3D(pol). To act as the primer for positive-strand RNA synthesis, the 3B peptides have to be uridylylated to form VPgpU(pU). For certain picornaviruses, it has been shown that this reaction is achieved by the 3D(pol) in the presence of the 3CD precursor plus an internal RNA sequence termed a cis-acting replication element (cre). The FMDV cre has been identified previously to be within the 5' untranslated region, whereas all other picornavirus cre structures are within the viral coding region. The requirements for the in vitro uridylylation of each of the FMDV 3B peptides has now been determined, and the role of the FMDV cre (also known as the 3B-uridylylation site, or bus) in this reaction has been analyzed. The poly(A) tail does not act as a significant template for FMDV 3B uridylylation.
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Affiliation(s)
- Arabinda Nayak
- BBSRC Institute for Animal Health, Pirbright, Woking, Surrey GU24 ONF, United Kingdom
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Boerner JE, Lyle JM, Daijogo S, Semler BL, Schultz SC, Kirkegaard K, Richards OC. Allosteric effects of ligands and mutations on poliovirus RNA-dependent RNA polymerase. J Virol 2005; 79:7803-11. [PMID: 15919933 PMCID: PMC1143668 DOI: 10.1128/jvi.79.12.7803-7811.2005] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Protein priming of viral RNA synthesis plays an essential role in the replication of picornavirus RNA. Both poliovirus and coxsackievirus encode a small polypeptide, VPg, which serves as a primer for addition of the first nucleotide during synthesis of both positive and negative strands. This study examined the effects on the VPg uridylylation reaction of the RNA template sequence, the origin of VPg (coxsackievirus or poliovirus), the origin of 3D polymerase (coxsackievirus or poliovirus), the presence and origin of interacting protein 3CD, and the introduction of mutations at specific regions in the poliovirus 3D polymerase. Substantial effects associated with VPg origin were traced to differences in VPg-polymerase interactions. The effects of 3CD proteins and mutations at polymerase-polymerase intermolecular Interface I were most consistent with allosteric effects on the catalytic 3D polymerase molecule. In conclusion, the efficiency and specificity of VPg uridylylation by picornavirus polymerases is greatly influenced by allosteric effects of ligand binding that are likely to be relevant during the viral replicative cycle.
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Affiliation(s)
- Joanna E Boerner
- Stanford University School of Medicine, Department of Microbiology and Immunology, Fairchild Science Building D309A, Stanford, CA 94305-5402, USA
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Nagashima S, Sasaki J, Taniguchi K. The 5'-terminal region of the Aichi virus genome encodes cis-acting replication elements required for positive- and negative-strand RNA synthesis. J Virol 2005; 79:6918-31. [PMID: 15890931 PMCID: PMC1112095 DOI: 10.1128/jvi.79.11.6918-6931.2005] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Aichi virus is a member of the family Picornaviridae. It has already been shown that three stem-loop structures (SL-A, SL-B, and SL-C, from the 5' end) formed at the 5' end of the genome are critical elements for viral RNA replication. In this study, we further characterized the 5'-terminal cis-acting replication elements. We found that an additional structural element, a pseudoknot structure, is formed through base-pairing interaction between the loop segment of SL-B (nucleotides [nt] 57 to 60) and a sequence downstream of SL-C (nt 112 to 115) and showed that the formation of this pseudoknot is critical for viral RNA replication. Mapping of the 5'-terminal sequence of the Aichi virus genome required for RNA replication using a series of Aichi virus-encephalomyocarditis virus chimera replicons indicated that the 5'-end 115 nucleotides including the pseudoknot structure are the minimum requirement for RNA replication. Using the cell-free translation-replication system, we examined the abilities of viral RNAs with a lethal mutation in the 5'-terminal structural elements to synthesize negative- and positive-strand RNAs. The results showed that the formation of three stem-loops and the pseudoknot structure at the 5' end of the genome is required for negative-strand RNA synthesis. In addition, specific nucleotide sequences in the stem of SL-A or its complementary sequences at the 3' end of the negative-strand were shown to be critical for the initiation of positive-strand RNA synthesis but not for that of negative-strand synthesis. Thus, the 5' end of the Aichi virus genome encodes elements important for not only negative-strand synthesis but also positive-strand synthesis.
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Affiliation(s)
- Shigeo Nagashima
- Department of Virology and Parasitology, Fujita Health University School of Medicine, Toyoake, Aichi 470-1192, Japan
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Egger D, Bienz K. Intracellular location and translocation of silent and active poliovirus replication complexes. J Gen Virol 2005; 86:707-718. [PMID: 15722531 DOI: 10.1099/vir.0.80442-0] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Replication of poliovirus (PV) genomic RNA in HeLa cells has previously been found to start at distinct sites at the nuclear periphery. In the present study, the earliest steps in the virus replication cycle, i.e. the appearance and intracellular translocation of viral protein and negative-strand RNA prior to positive-strand RNA synthesis, were followed. During translation, positive-strand RNA and newly synthesized viral protein presented as a dispersed endoplasmic reticulum (ER)-like pattern. Concomitant with translation, individual PV vesicle clusters emerged at the ER and formed nascent replication complexes, which contained newly synthesized negative-strand RNA. The complexes rapidly moved centripetally, in a microtubule-dependent way, to the perinuclear area to engage in positive-strand viral RNA synthesis. Replication complexes made transcriptionally silent with guanidine/HCl followed the anterograde membrane pathway to the Golgi complex within the microtubule-organizing centre (MTOC), whereas replication complexes active in positive-strand RNA synthesis were retained at the nuclear periphery. If the silent replication complexes that had accumulated at the MTOC were released from the guanidine block, transcription was not readily resumed. Rather, positive-strand RNA was redistributed back to the ER to start, after a lag phase, translation, followed by negative- and positive-strand RNA synthesis in replication complexes migrating to the nuclear periphery. As some of the findings appear to be in contrast to events reported in cell-free guanidine-synchronized translation/transcription systems, implications for the comparison of in vitro systems with the living cell are discussed.
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Affiliation(s)
- Denise Egger
- Institute for Medical Microbiology, University of Basel, Petersplatz 10, CH-4000 Basel, Switzerland
| | - Kurt Bienz
- Institute for Medical Microbiology, University of Basel, Petersplatz 10, CH-4000 Basel, Switzerland
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